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Biomedical subjects

G C Hall

Publications and source records attributed to G C Hall.

At least 37 records · Page 2Linked to original sources
PubMed1991

Toward a theory of sexual aggression: a quadripartite model.

Sexually aggressive behavior against adult females is an increasingly serious societal problem. The need for a unified theoretical model is addressed by integrating the elements of existing models into a quadripartite model in which the heterogeneity of sexual aggressors is accounted for by the prominence of potential etiological factors. The components of the model--physiological sexual arousal, cognitions that justify sexual aggression, affective dyscontrol, and personality problems--function as motivational precursors that increase the probability of sexually aggressive behavior. The relative prominence of these precursors within different sexually aggressive populations is used to define major subtypes.

Aggression↗
PubMed1991

Chemical and molecular weight analyses of prosthodontic soft polymers.

A number of studies have been made investigating the properties of dental prosthodontic soft polymer materials. In such materials, which are used as short-term denture soft liners, the polymer component is complexed with one or more plasticizers. This lowers the glass transition temperature, Tg, of the polymer by allowing greater chain mobility and produces a more flexible material. Little information is available relating to the polymer components of such soft-lining materials. The chemical composition and molecular-weight distribution of a polymer help to determine its ability to form a plasticized soft polymer-gel. In the present work, both pyrolysis depolymerization/gas chromatography (GC) and size exclusion chromatography (SEC) have been used to characterize 11 commercial polymer powders. By use of SEC and polymer standards having a narrow molecular-weight range, it has been possible for accurate molecular-weight distributions to be determined for all 11 powders. The peak molecular weights were found to be between 1.79 x 10(5) and 3.28 x 10(5). These values are above the molecular weight at which chain entanglement occurs. The polydispersity ratios (Mw/Mn) were between 2.09 and 4.48. Methacrylate polymers can be readily decomposed thermally to their constituent monomers, which, once recovered, can be analyzed by gas chromatography. The simple pyrolysis apparatus used in the present study was easily assembled and was capable of producing both qualitative and quantitative results. None of the commercial polymers analyzed gave methacrylate decomposition products with pendant chains greater than ethyl (-CH2-CH3). All of the commercial polymers successfully studied by the pyrolysis test method proved to be poly(ethyl [100-79%]/methyl [0-21%] methacrylate) polymers or co-polymers.

Chromatography, Gas↗
PubMed1991

Crevice corrosion products of dental amalgam.

The objective of this study was to determine the in vitro corrosion products that resulted from crevice corrosion of low- and high-copper dental amalgams. Specimens were potentiostatically polarized in a chloride-containing electrolyte while set against a PTFE surface to form a crevice. After 16 h, corrosion products were examined by light microscopy, SEM, EDS, and XRD. Analysis showed the presence of three previously reported products [Sn4(OH)6Cl2, SnO, and Cu2O] and a new product, CuCl, which formed on high-copper, gamma 2-free amalgams. Thermodynamic considerations show that CuCl is stable for the reported in vivo potentials of amalgam restorations and the high acidity and high chloride ion concentration associated with crevice corrosion.

Copper↗
PubMed1991

Three methods of developing MMPI taxonomies of sexual offenders.

In a sample of 261 state hospital sexual offenders, Minnesota Multiphasic Personality Inventory (MMPI) profiles did not differ for offenders with adult victims versus offenders with child victims when offender age was controlled. MMPI 2-point analyses for the whole sample revealed five common codes that were independent of victim maturity. The sample was randomly divided in half and subjected to a cluster-analytic procedure which revealed two MMPI clusters. The first cluster was unelevated, with Scale 4 as its high point. The second cluster had multiple elevations, with Scales 8, 4, 2, and 7 as the highest scales. These clusters were replicated in a cluster analysis of the second half of the sample. However, when the sample was recombined, the two clusters were not externally validated basis on demographic and criminological variables. The results suggest that common psychological variables among sexual offenders may have more discriminative value than victim maturity in developing sexual offender taxonomies.

Adult↗
PubMed1991

Introduction to special section on theories of sexual aggression.

Sexual aggression is a serious societal problem, yet treatments for sexual aggressors have generally been ineffective in part because of the lack of unified theories to guide treatment. This brief article introduces the Special Section, which includes five theories of sexual aggression.

Aggression↗
PubMed1990

A comparison of the risk of hypoglycemia between users of human and animal insulins. 1. Experience in the United Kingdom.

In a case-control study of 121 young insulin-dependent diabetics diagnosed as having an episode of hypoglycemia, the relative risk estimate comparing human with animal insulins was 0.8 (95% confidence interval 0.4, 1.6) controlling for age, general practice, and calendar time. We conclude that in this study population derived from general practices in the United Kingdom, the risk of hypoglycemia was no higher in users of human insulin than it was in users of animal insulins.

Adolescent↗
PubMed1989

Sexual arousal and arousability in a sexual offender population.

Assessed penile erections in response to descriptions of consenting sex, rape, and nonsexual assault among 78 inpatient male sexual offenders. All forms of sexual arousal were positively correlated, and sexual arousal to consenting stimuli exceeded arousal to coercive stimuli. Subjects who were able to completely inhibit their arousal exhibited less arousal to sexual assault stimuli than did subjects who were unable to completely inhibit arousal when both groups were not instructed to inhibit arousal. Inhibitory ability covaried with victim maturity, and with months spent in a treatment program. The maturity of the victims in the subjects' sexual offenses was not significantly related to sexual arousal. Thus, sexual offenders' sexual arousal as assessed by physiological measures may be more a function of arousability variables than of actual offending behaviors.

Adult↗
PubMed1989

Self-reported hostility as a function of offense characteristics and response style in a sexual offender population.

The Buss-Durkee Hostility Inventory (BDHI), the Hostility Toward Women Scale (HTWS), and the Minnesota Multiphasic Personality Inventory (MMPI) Social Desirability and Defensiveness scales were examined in a sample of 239 sexual offenders, 23 of whom had previously been studied. Sexual offenders against adolescents and adults had higher BDHI scores than sexual offenders against children. However, multiple regression equations revealed that the MMPI Defensiveness scale accounted for more of the shared variance in both types of self-reported hostility than did the maturity of the subjects' victims or the level of force used in the commission of the sexual offenses. Social desirability was significantly associated with the HTWS but not with the BDHI.

Adolescent↗
PubMed1989

Correlation of dental amalgam crevice corrosion with clinical ratings.

In vitro corrosion behavior of gamma 2-containing and gamma 2-free dental amalgams was examined under crevice conditions which simulated the amalgam-tooth interface. By means of potentiostatic testing, current-density/time behavior and integrated anodic current were measured for 16 hr. All of the amalgams demonstrated crevice corrosion susceptibility. Crevice corrosion propagation for gamma 2-free vs. gamma 2-containing amalgams was characterized by lower acceleration and maximum rates during the most dynamic period. Integrated anodic current results were correlated with marginal breakdown ratings reported in two clinical investigations. Strong and significant coefficients were found between integrated current and marginal breakdown ratings when gamma 2-containing and gamma 2-free amalgams were correlated as a single group, but not when correlated separately.

Corrosion↗
PubMed1989

WAIS-R and MMPI profiles of men who have sexually assaulted children: evidence of limited utility.

Wechsler Adult Intelligence Scale-Revised (WAIS-R) data were compiled on 101 male sexual offenders of children, and Minnesota Multiphasic Personality Inventory (MMPI) profiles were compiled for a subsample of 81 of these subjects in a replication and extension of the Hall, Maiuro, Vitaliano, and Proctor (1986) MMPI study. The MMPI profiles were heterogeneous and had multiple elevations. No significant relationships between the WAIS-R Full Scale IQ, WAIS-R Performance IQ Minus Verbal IQ Index, or the MMPI scales, and offense characteristics were obtained. These results support the hypothesis of Hall et al. (1986) that psychometric instruments may be of limited utility in characterizing or differentiating among sexual offenders on the basis of criminological variables.

Adolescent↗
PubMed1985

The response of dental amalgam to dynamic loading.

A conventional (gamma 2-containing) dental amalgam was fatigue-tested at 1800 and 80 cycles/min, employing uni-axial, sinusoidal loading, with R = -8. Compressive, tensile, and creep tests were conducted to characterize the alloy's static mechanical behavior. Tests were performed at 37 degrees C on specimens which were aged for seven days, at 37 degrees C. Fatigue-tested specimens were microscopically examined for fracture surface appearance and crack path. The amalgam demonstrated a frequency dependence and a significant reduction in fracture strength due to fatigue loading. The fatigue crack path was primarily intergranular in the gamma 1 phase and inclined at approximately 45 degrees to the principal stress axis. These observations are characteristic of some metals when subjected to low-frequency, elevated temperature testing where significant grain boundary sliding occurs, and therefore suggest a creep-fatigue interaction for this alloy.

Dental Amalgam↗
PubMed1983

Regulation of the aromatic pathway in the cyanobacterium Synechococcus sp. strain Pcc6301 (Anacystis nidulans).

A pattern of allosteric control for aromatic biosynthesis in cyanobacteria relies upon early-pathway regulation as the major control point for the entire branched pathway. In Synechococcus sp. strain PCC6301 (Anacystis nidulans), two enzymes which form precursors for L-phenylalanine biosynthesis are subject to control by feedback inhibition. 3-Deoxy-D-arabino-heptulosonate 7-phosphate synthase (first pathway enzyme) is feedback inhibited by L-tyrosine, whereas prephenate dehydratase (enzyme step 9) is feedback inhibited by L-phenylalanine and allosterically activated by L-tyrosine. Mutants lacking feedback inhibition of prephenate dehydratase excreted relatively modest quantities of L-phenylalanine. In contrast, mutants deregulated in allosteric control of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase excreted large quantities of L-phenylalanine (in addition to even greater quantities of L-tyrosine). Clearly, in the latter mutants, the elevated levels of prephenate must overwhelm the inhibition of prephenate dehydratase by L-phenylalanine, an effect assisted by increased intracellular L-tyrosine, an allosteric activator. The results show that early-pathway flow regulated in vivo by 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase is the dominating influence upon metabolite flow-through to L-phenylalanine. L-Tyrosine biosynthesis exemplifies such early-pathway control even more simply, since 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase is the sole regulatory enzyme subject to end-product control by L-tyrosine.

3-Deoxy-7-Phosphoheptulonate Synthase↗
PubMed1982

Biochemical diversity for biosynthesis of aromatic amino acids among the cyanobacteria.

We examined the enzymology and regulatory patterns of the aromatic amino acid pathway in 48 strains of cyanobacteria including representatives from each of the five major grouping. Extensive diversity was found in allosteric inhibition patterns of 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase, not only between the major groupings but also within several of the generic groupings. Unimetabolite inhibition by phenylalanine occurred in approximately half of the strains examined; in the other strains unimetabolite inhibition by tyrosine and cumulative, concerted, and additive patterns were found. The additive patterns suggest the presence of regulatory isozymes. Even though both arogenate and prephenate dehydrogenase activities were found in some strains, it seems clear that the arogenate pathway to tyrosine is a common trait that has been highly conserved among cyanobacteria. No arogenate dehydratase activities were found. In general, prephenate dehydratase activities were activated by tyrosine and inhibited by phenylalanine. Chorismate mutase, arogenate dehydrogenase, and shikimate dehydrogenase were nearly always unregulated. Most strains preferred NADP as the cofactor for the dehydrogenase activities. The diversity in the allosteric inhibition patterns for 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase, cofactor specificities, and the presence or absence of prephenate dehydrogenase activity allowed the separation of subgroupings within several of the form genera, namely, Synechococcus, Synechocystis, Anabaena, Nostoc, and Calothrix.

3-Deoxy-7-Phosphoheptulonate Synthase↗